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Nonlinear Dynamics of Production Systems
09 Apr 2004-
TL;DR: This reference work provides a comprehensive insight into past developments in the application of non-linear dynamics, such as production systems in the manufacturing and process engineering, mechanical engineering and plant construction and automation technology.
Abstract: This reference work provides a comprehensive insight into past developments in the application of non-linear dynamics, such as production systems in the manufacturing and process engineering, mechanical engineering and plant construction and automation technology. As such, it is the first publication to document the successful implementation of non-linear dynamics into current tasks or problems of engineering thus far unsolved. The interdisciplinary team of contributors from research and industry establishes ties between mechanical methods of manufacturing and new methods reaching the dynamics of production lines and complete production systems.
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TL;DR: In this paper, a self-organization approach is proposed to coordinate traffic flows at intersections based on the observation of self-organized oscillations of pedestrian flows at bottlenecks.
Abstract: Based on fluid-dynamic and many-particle (car-following) simulations of traffic flows in (urban) networks, we study the problem of coordinating incompatible traffic flows at intersections. Inspired by the observation of self-organized oscillations of pedestrian flows at bottlenecks, we propose a self-organization approach to traffic light control. The problem can be treated as a multi-agent problem with interactions between vehicles and traffic lights. Specifically, our approach assumes a priority-based control of traffic lights by the vehicle flows themselves, taking into account short-sighted anticipation of vehicle flows and platoons. The considered local interactions lead to emergent coordination patterns such as 'green waves' and achieve an efficient, decentralized traffic light control. While the proposed self-control adapts flexibly to local flow conditions and often leads to non-cyclical switching patterns with changing service sequences of different traffic flows, an almost periodic service may evolve under certain conditions and suggests the existence of a spontaneous synchronization of traffic lights despite the varying delays due to variable vehicle queues and travel times. The self-organized traffic light control is based on an optimization and a stabilization rule, each of which performs poorly at high utilizations of the road network, while their proper combination reaches a superior performance. The result is a considerable reduction not only in the average travel times, but also of their variation. Similar control approaches could be applied to the coordination of logistic and production processes.
253 citations
TL;DR: In this article, the authors study several conceivable production strategies to stabilize supply chains, expressed by different specifications of the management function controlling the production speed in dependence of the stock levels, and demonstrate that the anticipation of future stock levels can stabilize the supply system, given the forecast horizon τ is long enough.
Abstract: Due to delays in the adaptation of production or delivery rates, supply chains can be dynamically unstable with respect to perturbations in the consumption rate, which is known as “bull-whip effect”. Here, we study several conceivable production strategies to stabilize supply chains, which is expressed by different specifications of the management function controlling the production speed in dependence of the stock levels. In particular, we will investigate, whether the reaction to stock levels of other producers or suppliers has a stabilizing effect. We will also demonstrate that the anticipation of future stock levels can stabilize the supply system, given the forecast horizon τ is long enough. To show this, we derive linear stability conditions and carry out simulations for different control strategies. The results indicate that the linear stability analysis is a helpful tool for the judgement of the stabilization effect, although unexpected deviations can occur in the non-linear regime. There are also signs of phase transitions and chaotic behavior, but this remains to be investigated more thoroughly in the future.
88 citations
Cites background from "Nonlinear Dynamics of Production Sy..."
...The assumed model consists of a series of u suppliers i, which receive products from the next “upstream” supplier i − 1 and generate products for the next “downstream” supplier i + 1 (see Fig....
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...Section 6 finally summarizes our findings, discusses them in a broader context, and indicates further research directions....
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...Here, we study several conceivable production strategies to stabilize supply chains, which is expressed by different specifications of the management function controlling the production speed in dependence of the stock levels....
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...Let us derive the long wave expansion of z, which is determined order by order around ik ≈ 0....
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TL;DR: In this article, a multiple degree of freedom model for chatter prediction in turning, based on compliance between the cutting tool and the workpiece, is presented and a linear stability analysis of the model in the frequency domain is performed and a method to construct typical stability charts is obtained.
Abstract: Chatter is a common vibration problem that limits productivity of machining processes, since its large amplitude vibrations causes poor surface finishing, premature damage and breakage of cutting tools, as well as mechanical system deterioration. This phenomenon is a condition of instability that has been classified as a self-excited vibration problem, which shows a nonlinear behavior characterized by the presence of limit cycles and jump phenomenon. In addition, subcritical Hopf and flip bifurcations are mathematical interpretations for loss of stability. Regeneration theory and linear time delay models are the most widely accepted explanations for the onset of chatter vibrations. On the other hand, models based on nonlinearities from structure and cutting process have been also proposed and studied under nonlinear dynamics and chaos theory. However, on both linear and nonlinear formulations usually the compliance between the workpiece and cutting tool has been ignored. In this work, a multiple degree of freedom model for chatter prediction in turning, based on compliance between the cutting tool and the workpiece, is presented. Hence, a better approach to the physical phenomenon is expected, since the effect of the dynamic characteristics of the cutting tool is also taken into account. In this study, a linear stability analysis of the model in the frequency domain is performed and a method to construct typical stability charts is obtained. The effect of the dynamics of the cutting tool on the stability of the process is analyzed as well.
85 citations
01 Jan 2006
TL;DR: In this article, the authors investigate the interaction networks responsible for the cascade-like spreading of disasters, and identify other fields where network theory could help to improve disaster response management, including disaster management.
Abstract: We discuss why disasters occur more frequently and are more serious than expected according to a normal distribution. Moreover, we investigate the interaction networks responsible for the cascade-like spreading of disasters. Such causality networks allow one to estimate the development of disasters with time, to give hints about when to take certain actions, to assess the suitability of alternative measures of emergency management, and to anticipate their side effects. Finally, we identify other fields where network theory could help to improve disaster response management.
83 citations
TL;DR: It is shown that, under certain assumptions, the control of nodes can be mapped to a network of phase-oscillators in a self-organising, decentralised control method for material flows in networks.
Abstract: We present a self-organising, decentralised control method for material flows in networks. The concept applies to networks where time sharing mechanisms between conflicting flows in nodes are required and where a coordination of these local switches on a system-wide level can improve the performance. We show that, under certain assumptions, the control of nodes can be mapped to a network of phase-oscillators. By synchronising these oscillators, the desired global coordination is achieved. We illustrate the method in the example of traffic signal control for road networks. The proposed concept is flexible, adaptive, robust and decentralised. It can be transferred to other queuing networks such as production systems. Our control approach makes use of simple synchronisation principles found in various biological systems in order to obtain collective behaviour from local interactions.
80 citations